Upgrading processes are typically catalytic reactions that remove unwanted molecules from petroleum distillates during the petroleum refining process. Oxidative demercaptization, which is also known as “sweetening” in view of the effect it has on the odor of the hydrocarbon liquid composition, is an important upgrading process. This process removes foul smelling, toxic, corrosive and unwanted sulfur-containing molecules, such as mercaptans, from the fuel stream by converting them into less harmful and odorous disulfides. It may also remove other unwanted trace polar compounds such as napthenates and phenols from the hydrocarbon liquid composition.
In the past various processes and catalysts have been used for sweetening hydrocarbon mixtures. However, today the Merox™ process, available from UOP LLC of Des Plaines, Ill., USA, has almost entirely replaced those older systems. The Merox process has been described in detail, and is well known to the person skilled in the art (see for example, U.S. Pat. No. 7,087,547; and “Merox Process for Kerosene/Jet Fuel Sweetening”—Process Technology and Equipment, (2003), published by UOP LLC).
As part of the Merox process, clay treatment (or clay filtration; e.g. using a clay treater) removes unwanted contaminants from a hydrocarbon liquid composition. Typically, the fuel is passed through a clay treater, where it comes into contact with the surface of the clay. Polar and ionic compounds, including surfactants, organometallic compounds, particulates, corrosion inhibitors, and other compounds within the fuel are adsorbed onto the surface of the clay and, thereby, removed from the fuel. Clay treatment is often used downstream of other upgrading units within the Merox process, in order to remove surfactants and other ionic species that may be introduced into the hydrocarbon composition during those processes.
Clay treatment units known in the art include concrete or clay that is used at the bottom head of the unit to support various functional components of the unit, including the “collector,” which is a plurality of cylindrical conduits that extend horizontally within the clay bed of the treatment unit. After fabrication at a fabrication site, clay treatment units are typically transported in a horizontal (as opposed to vertical, upright) fashion, and because of this, the fabricator cannot put the concrete inside the clay treatment unit at the fabrication site. Accordingly, it becomes necessary to install the clay treatment unit at the refinery site, and then to add the concrete to the bottom head thereof and install the collector. This installation process increases the amount of work required at the refinery site, as compared to putting the concrete and the collector in the unit at the fabrication site.
A current trend in the petroleum processing industry is that of “modularization,” wherein petroleum processing units are fabricated in modular form such that the amount of installation work necessary at the installation site is minimized. For example, much of the Merox processing system is currently available in modular form, which reduces the lead time between fabrication, installation, and ultimate operation-ready status. Due to the requirement of concrete addition after installation, the concept of modularization has proved time-consuming to implement as applied to clay treatment apparatuses.
Accordingly, it is desirable to provide improved clay treatment apparatuses for removing unwanted contaminants from a hydrocarbon liquid composition and methods employing the use of such apparatuses. Furthermore, it is desirable to provide such clay treatment apparatuses in modular form to reduce the on-site work required to install such apparatuses. Still further, it is desirable to provide such clay treatment apparatuses that do not require concrete as a collector support at the bottom head portion thereof. Furthermore, other desirable features and characteristics of the presently disclosed embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.